Résumé des exemples de codes de fonction d'interception de chaînes chinoises adaptés à différents encodages

<?php 
//截取中文字符串 
function mysubstr($str, $start, $len) { 
$tmpstr = ""; 
$strlen = $start + $len; 
for($i = 0; $i < $strlen; $i++) { 
if(ord(substr($str, $i, 1)) > 0xa0) { 
$tmpstr .= substr($str, $i, 2); 
$i++; 
} else 
$tmpstr .= substr($str, $i, 1); 
} 
return $tmpstr; 
} 
?>

<?php 
//截取utf8字符串 
function utf8Substr($str, $from, $len) 
{ 
return preg_replace(&#39;#^(?:[\x00-\x7F]|[\xC0-\xFF][\x80-\xBF]+){0,&#39;.$from.&#39;}&#39;. 
&#39;((?:[\x00-\x7F]|[\xC0-\xFF][\x80-\xBF]+){0,&#39;.$len.&#39;}).*#s&#39;, 
&#39;$1&#39;,$str); 
} 
?>

function csubstr($str, $start=0, $length, $charset="utf-8", $suffix=true)   
{   
 if(function_exists("mb_substr"))   
  return mb_substr($str, $start, $length, $charset);   
 $re['utf-8']   = "/[\x01-\x7f]|[\xc2-\xdf][\x80-\xbf]|[\xe0-\xef][\x80-\xbf]{2}|[\xf0-\xff][\x80-\xbf]{3}/";    
 $re['gb2312'] = "/[\x01-\x7f]|[\xb0-\xf7][\xa0-\xfe]/";   
 $re['gbk']   = "/[\x01-\x7f]|[\x81-\xfe][\x40-\xfe]/";   
 $re['big5']   = "/[\x01-\x7f]|[\x81-\xfe]([\x40-\x7e]|\xa1-\xfe])/";    
 preg_match_all($re[$charset], $str, $match);   
 $slice = join("",array_slice($match[0], $start, $length));   
 if($suffix) return $slice."…";   
 return $slice;   
}

<?php 
function sysSubStr($String,$Length,$Append = false) 
{ 
if (strlen($String) <= $Length ) 
{ 
return $String; 
} 
else 
{ 
$I = 0; 
while ($I < $Length) 
{ 
$StringTMP = substr($String,$I,1); 
if ( ord($StringTMP) >=224 ) 
{ 
$StringTMP = substr($String,$I,3); 
$I = $I + 3; 
} 
elseif( ord($StringTMP) >=192 ) 
{ 
$StringTMP = substr($String,$I,2); 
$I = $I + 2; 
} 
else 
{ 
$I = $I + 1; 
} 
$StringLast[] = $StringTMP; 
} 
$StringLast = implode("",$StringLast); 
if($Append) 
{ 
$StringLast .= "..."; 
} 
return $StringLast; 
} 
}$String = "www.at0915.cn"; 
$Length = "18"; 
$Append = false; 
echo sysSubStr($String,$Length,$Append); 
?>